Telephone receiver



Nov. 23, 1937. A. A. DUNCAN 2,099,727

' TELEPHONE RECEIVER Filed April 5, 1954 30 33 ab 35 6 as aq a7 39 g 33I I I 1 1716 6 7 11 15 b is 10 Hf y n" W il 'H 1 10 I I VLQJ l A n g? 255 :FIEB

IN VEN TOR a 2&2

A TTORNE Y Patented Nov. 23, 1937 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to improvements in magnetically operated soundreproducing apparatus and while intended for use generally wherever itmay be advantageously employed, it is particularly adapted for use intelephone receivers and loud speakers in which connection it will beillustrated in the drawing and hereinafter specifically described.

Objects of the invention are to provide a loud speaking electricreceiver of simple construction which may be manufactured at a low costand which will be eificient in use.

Other objects of the invention are to provide a receiver including adiaphragm having electromagnetic means for vibrating said diaphragm anda permanent magnet for amplifying the force of the electromagnetic meansand to provide an improved arrangement of parts whereby the permanentmagnet will operate to greatly increase the effect of the electromagnetwithout in any way distorting or otherwise effecting the normal positionof the diaphragm.

Other objects are to provide a sound reproducing device which willinclude a diaphragm, an electromagnet having an armature operativelyconnected to the diaphragm and a permanent magnet arranged topermanently maintain the armature in a magnetized condition and therebyprovide an armature having polarized ends each positioned in oppositepolar relation to the poles of the electromagnet.

The accomplishment of the above and additional objects is attained bythe novel construction, combination and arrangement of parts hereinafterdescribed and illustrated in the accompanying drawing wherein there isshown a preferred embodiment of the invention, it being understood thatchanges and modifications may be made or resort had to substitutionswhich come within the scope of the claims hereunto appended.

In the drawing:

Figure 1 is a central, vertical, sectional view of a loud speaking unitconstructed in accordance with this invention,

Figure 2 is a plan view showing the cover and diaphragm removed.

Proceeding now to a detailed description of the invention with referenceto the particular adaptation thereof disclosed in the drawing, thenumeral 3 is used generally to denote a casing which is preferablyformed of brass or other non-magnetic material. a The casing 3 isprovided with a relatively small closed end portion 4 which is offsetlarger to provide an annular shoulder 5 and a relatively largerintermediate portion 6. The wall of the casing is offset larger at theend of the portion 6 to form the annular shoulder and the larger mouthportion 8.

The portion 4 is provided with an end wall 9 and an electromagnet I0 issuitably secured to the central portion thereof. As shown in thedrawing, the magnet I0 consists of two coils Ma and lOb wound on ahorseshoe core H. The forks of the core II project upwardly in spaced,parallel relation and terminate in outwardly turned horizontal portionsIla and Mb. The end portion ll forms the positive pole piece of theelectromagnet l0 and the end portion llb the negative pole piecethereof. The ends of the wire'l2 forming the coils Illa and lflbterminate in suitable connecting terminals l3 and 14 whereby the samemay be operatively interposed in an electric circuit.

The numeral I5 denotes a permanent horseshoe magnet which is positionedon the shoulder 5 and extends around approximately one-half of thecircumference of the casing 3. The positive end of the magnet I5 isprovided with a spring bracket I6 which is suitably secured to the innerside thereof and terminates in a horizontal portion which is positionedwith the medial line thereof disposed along the diameter of the casingpassing over the pole pieces I la and Nb. A relatively thicker soft ironpole piece I! is secured to the inwardly projecting portion of thebracket [6 to extend in the same general direction. The pole piece I!extends over the outer portion of the pole piece Ill) and is disposed inoperative spaced relation thereto.

The negative end portion I5?) is provided with a similar bracket l8which is suitably secured to the inner face thereof with thelongitudinal portion of the bracket l8 positioned with the medial linethereof disposed on the same diameter of the casing as the bracket Hi.The numeral l9 denotes a negative iron pole piece which is similar tothe positive pole piece I! and is secured to the inwardly projecting endof the spring bracket I8 to extend in the same general direction withthe inner end thereof projecting over the outer portion of the polepiece Ha in operative spaced relation thereto.

The numeral 2!] denotes an armature of soft iron which is positionedbetween the pole pieces I! and I9 with the ends thereof in operative,spaced relation thereto. The numeral 2| denotes a thin brass springwhich is secured to the amplified resulting in a louder,

pole'pieces l1 and I 9 and to the armature 20 to secure the same in anoperative position. The spring brackets l6 and ii are composed of magnetically conductive material and V the said brackets and the'brassstrip 2| support the armature 20 so that it may be freely vibrated whensubjected to theintermittent attraction of the magnet 10.

The numeral 22 denotes a diaphragm which is preferably composed of mica,but which may be formed of any suitable material. The marginal portionsof the diaphragm 22 are supported on the shoulder 1 between the gaskets23 and 24. V closure member 25 having a cylindrical flange is fittedrinthe mouth portion 8 with the axial end thereof in forced contact withthe gasket 24 thus firmly securing the diaphragm 22 in an operativeposition in the casing 3.

The numeral 29 denotes a connecting member.

which is threaded or otherwise secured to the armature 20 with the upperend thereof extending through the central portion of the diaphragm 22. VV

The connecting member-21 is securedto the diaphragm 22 by thenuts 28 and29 which are operated to firmly secure the members 21 in place withoutnormally distorting the diaphragm 22. The closuremember is provided witha suitableopening 3D which'may be provided with a suitablenipple 3|. o

In operation, the terminals l3 and H are operatively connected in atelephone circuit. 'When subjected to the action of an intermittentcurrent the magnet 10 will be energized attracting the pole piece 20 andoperatively vibrating the dia-' phragm 22. 7

1 Itwill be seen that the pole piece llw is positive, the pole piece l'9negative and the polerpiece llb negative and the pole piece I 1positive; the attraction of the electromagnet' III will be greatly tionof sound.- 3 V 7 It will also be seen that use of opposite polarization'to intensify the action of a permanent magnet has been accomplishedwithout substan tial distortion of the diaphragm 22 when the'electromagn'et is'not in operation thus providing an amplified receiverwhich will operate to preproduce sound without distortion.

clearer reproduc 1.'In a telephone receiver; an electromagnet:

' having a horseshoe core terminating at each end thereof in laterallyprojecting pole pieces, a soft iron armature positioned in spacedoperative relation to said pole pieces, apermanent magnet having aspring bracket on each end thereof, a soft iron pole piece oneach'bracket, said armature mounted with its ends in close, spacedrelation to and in the lateral plane of the pole pieces of saidpermanent magnet, each pole piece of said permanent magnet beingpositioned 'in close spaced relation to the pole piece at the oppositepole of the electromagnet, a diaphragm and member operatively connectingthe armature to the diaphragm.

' 2. In a telephone receiver, an electromagnet" having opposite polespresented in the same direction and having oppositely projecting flatpole pieces, a soft iron armature positioned in spacedoperativetrelation to said pole pieces; a permanent horseshoe magnet, aspring :extension on each end thereof, a soft iron pole piece on the endof each extension, said armature mountedin spaced relation between saidsoft iron pole pieces; a thin strip of magnetically non-conductive maaterial connecting said armature to the soft iron pole pieces, adiaphragm and means operatively connecting said armatureto saiddiaphragm.

3. In a telephone receiver, an electromag et having opposite polespresented in the same direction and having oppositely projecting flatpole pieces, a soft iron armature positioned in spaced, operativerelation to said pole pieces; a permanent horseshoe magnet, a springextension on each end thereof, a soft iron'pole piece on the end of eachextension, said armature mounted in spaced relation between said softiron polepiec'es, ;a thin strip of magnetically non-conductivemapermanent magnet, a diaphragm and means 0p eratively ,connecting saidarmature to said diaphragm. V

ARCHIBALD A. DUNCAN.

